This application is based on Application No. 2002-005911, filed in Japan on Jan. 15, 2002, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a fuel injection control device for an internal combustion engine, and particularly to a fuel injection control device for an internal combustion engine in a fuel returnless system.
2. Description of the Related Art
FIG. 9 is a block diagram showing a conventional fuel injection control device for an internal combustion engine in a fuel returnless system.
In the figure, reference numeral 1 denotes an internal combustion engine, reference numeral 2 denotes a cylinder, reference numeral 3 denotes a piston, reference numeral 4 denotes a cylinder head, reference numeral 5 denotes a combustion chamber, reference numeral 6 denotes an engine control unit, reference numeral 7 denotes an inlet port, reference numeral 8 denotes an inlet valve, reference numeral 9 denotes an exhaust port, reference numeral 10 denotes an exhaust valve, reference numeral 11 denoted an injector (fuel injection valve), reference numeral 12 denotes a sparking plug, reference numerals 13 and 14 denote actuators, reference numeral 15 denotes a fuel tank, reference numeral 16 denotes a fuel pressure regulator, reference numeral 17 denotes a fuel pipe, reference numeral 18 denotes an inlet manifold, reference numeral 19 denotes an inlet pipe pressure sensor, reference numeral 20 denotes an atmospheric pressure sensor, reference numeral 21 denotes a fuel pump, and reference numeral 22 denotes a delivery pipe.
The engine control unit 6 includes correction coefficient computation means for computing a fuel injection quantity correction coefficient according to a difference between an inlet pipe pressure and an atmospheric pressure detected by the inlet pipe pressure sensor 19 and the atmospheric sensor 20, and fuel injection amount correction means for correcting a fuel injection quantity according to the fuel injection quantity correction coefficient, and it drives the injector 11 in the corrected fuel injection quantity.
In the above-described conventional controller, a volume intake air quantity equivalent value is obtained by an inlet pipe pressure detected by the inlet pipe pressure sensor, but an error from an actual mass intake air quantity sometimes occurs due to influences of intake air temperature, exhaust recirculation gas (EGR) and the like, and when an accurate intake air quantity is to be measured, it is necessary to provide an intake air quantity sensor. However, in this case, if conventional correction of fuel pressure is to be carried out based on the inlet pipe pressure and the atmospheric pressure detected by the inlet pipe pressure sensor and the atmospheric sensor, the inlet pipe pressure sensor, which becomes unnecessary as a result that air quantity measurement with high accuracy is performed, is needed again, whereby the system becomes expensive.
If the correction of the fuel injection quantity based on fuel pressure according to the difference between the inlet pipe pressure and the atmospheric pressure is not carried out in the fuel injection control device using the intake air quantity sensor to measure the above-described intake air quantity with high accuracy, accuracy of the fuel injection quantity reduces sharply.
When exhaust gas recirculation equipment, a variable valve timing mechanism and the like are provided in a fuel injection control device using the intake air quantity sensor as described above, even if the same quantity of mass intake air is detected in the intake air quantity sensor, the inlet pipe pressure changes according to the quantities of an outer exhaust recirculation gas by the exhaust gas recirculation equipment and an inner exhaust recirculation gas by the variable valve timing mechanism. In this case, accuracy of a fuel injection quantity reduces sharply, if the correction of the inlet pipe pressure estimated with rotational speed and filling efficiency, which is used for fuel pressure correction, by exhaust gas recirculation control quantity and variable valve timing control quantity is not carried out and the correction of the fuel injection quantity by fuel pressure using the corrected inlet pipe pressure is not carried out.
The present invention is made to eliminate the above-described disadvantage, and its object is to provide a fuel injection control device for an internal combustion engine that is less expensive with high accuracy.
The fuel injection control device for the internal combustion engine according to the invention is a fuel injection control device for an internal combustion engine for supplying fuel at a constant pressure to an injector of each cylinder via a fuel pipe and a delivery pipe by a fuel pump and a fuel pressure regulator disposed in a fuel tank of the internal combustion engine, and includes rotational speed detection means for detecting rotational speed of the aforesaid internal combustion engine, intake air quantity detection means for detecting an air quantity taken into the aforesaid internal combustion engine, atmospheric pressure detection means for detecting atmospheric pressure; and correction means for estimating an inlet pipe pressure of the internal combustion engine from the detected rotational speed and intake air quantity, computing a fuel injection quantity fuel pressure correction coefficient according to a difference between the estimated inlet pipe pressure and the aforementioned detected atmospheric pressure, and correcting a fuel injection quantity based on the computed fuel injection quantity fuel pressure correction coefficient.
The fuel injection control device for the internal combustion engine according to the invention includes control means for controlling a recirculation quantity of exhaust gas recirculation equipment, and the aforesaid correction means corrects the inlet pipe pressure estimated from the detected rotational speed and intake air quantity according to the aforementioned recirculation quantity, computes the fuel injection quantity fuel pressure correction coefficient according to the difference between the corrected inlet pipe pressure and the detected atmospheric pressure, and corrects the fuel injection quantity according to the computed fuel injection quantity fuel pressure correction coefficient.
The fuel injection control device for the internal combustion engine according to the invention includes control means for controlling a variable valve timing of a variable valve timing mechanism, and the aforesaid correction means corrects the inlet pipe pressure estimated from the aforementioned detected rotational speed and intake air quantity according to the aforementioned variable valve timing, computes the fuel injection quantity fuel pressure correction coefficient according to the difference between the corrected inlet pipe pressure and the aforementioned detected atmospheric pressure, and corrects the fuel injection quantity according to the computed fuel injection quantity fuel pressure correction coefficient.
The fuel injection control device for the internal combustion engine according to the invention is a fuel injection control device for an internal combustion engine for supplying fuel at a constant pressure to an injector of each cylinder via a fuel pipe and a delivery pipe by a fuel pump and a fuel pressure regulator disposed in a fuel tank of the internal combustion engine, and includes rotational speed detection means for detecting rotational speed of the aforesaid internal combustion engine, intake air quantity detection means for detecting an air quantity taken into the aforesaid internal combustion engine, throttle valve travel detection means for detecting an valve travel of a throttle valve of the aforesaid internal combustion engine, inlet pipe pressure detection means for detecting an inlet pipe pressure of the aforesaid internal combustion engine, and correction means for estimating atmospheric pressure from the detected inlet pipe pressure, rotational speed, throttle valve travel and intake air quantity, computing a fuel injection quantity fuel pressure correction coefficient according to a difference between the estimated atmospheric pressure and the aforesaid detected inlet pipe pressure, and correcting a fuel injection quantity according to the computed fuel injection quantity fuel pressure correction coefficient.
The fuel injection control device for the internal combustion engine according to the invention is a fuel injection control device for an internal combustion engine for supplying fuel at a constant pressure to an injector of each cylinder via a fuel pipe and a delivery pipe by a fuel pump and a fuel pressure regulator disposed in a fuel tank of the internal combustion engine, and includes rotational speed detection means for detecting rotational speed of the aforesaid internal combustion engine, intake air quantity detection means for detecting an air quantity taken into the aforesaid internal combustion engine, throttle valve travel detection means for detecting an valve travel of a throttle valve of the aforesaid internal combustion engine, and correction means for estimating atmospheric pressure from the detected rotational speed, throttle valve travel and intake air quantity and estimating an inlet pipe pressure of the internal combustion engine from the aforementioned detected rotational speed and intake air quantity, computing a fuel injection quantity fuel pressure correction coefficient according to a difference between the estimated atmospheric pressure and inlet pipe pressure, and correcting a fuel injection quantity according to the computed fuel injection quantity fuel pressure correction coefficient.